Power conditioners typically condition alternating current (AC) power from a power source prior to delivering the conditioned power to a load. Such conditioning may include noise filtration and transient voltage surge suppression, among other things. Certain power conditioner circuits incorporate various sensors to monitor power quality and/or power consumption and, in certain cases, take a specific action when the power quality fails to meet specified criteria. While power conditioners are intended to protect and improve the performance of connected equipment, power related issues can still occur, particularly when stringent power quality criteria are to be met across multiple system variables. Thus, the cause of persistent equipment malfunctions may be rooted in a quite subtle power problem, e.g., harmonic distortion affecting a zero-cross voltage feature. Often, the only way many of these problems can be properly diagnosed is by displaying the line voltage on an oscilloscope. Unfortunately, many installations in which power conditioners are deployed are not equipped with oscilloscopes. Thus, the need has been felt for an oscilloscope that can be controlled via a portable terminal, such as a laptop computer, but with data acquisition circuitry incorporated into the power conditioner itself for diagnosing power related issues.